What is a Shear Test, and Why Is It Important?

The strength of our materials is something we may all take for granted, but hundreds of hours of specialist research and engineering are behind all of our greatest innovations.

From the cars we drive to the food we eat, shear testing plays a key role in ensuring the durability, safety, and reliability of structures, vehicles, and products worldwide.

But let's not get ahead of ourselves. What is shear testing, and how does it work?

In this blog, we'll give you everything you need to know about shear testing, including the types of tests, what they're used for, and where you can find the best equipment for your shear testing applications.

What is shear testing?

The shear test is a mechanical test used to evaluate the behavior of materials when placed under 'shear stress'.

Shear stress is a type of stress that causes two surfaces or two parts of the same surface to move past each other in opposite directions.

For example, shear stress occurs when cutting material with scissors. Force is applied by two blades that slide past each other, and the material being cut is subject to a concentrated shear force. The stronger the material, the more force is required to cut it.

Testers can use this same theory to find out information about a material. The data collected from a shear test experiment indicates the shear properties of a material.

Different test setups are suited to different materials and industries and reflect the type of strain a substance will be under during everyday use.

What does a shear test show?

The shear test provides vital information about a material's properties, including the shear modulus, shear strength, and shear strain.

1. Shear modulus testing: The shear modulus (also known as the modulus of elasticity) measures a material's rigidity and stiffness in response to a shear test. It indicates how well a material can withstand deformation when under shear stress.
2. Shear strength testing: A material's shear strength describes the maximum load a material can withstand before failure. Shear strength is essential data for structural engineers, as it shows the maximum shear stress a building material can resist before it breaks.
3. Shear strain testing: Shear strain measures how much a material twists, bends, or slides when a predetermined amount of force is applied. Shear strain indicates how much flexibility a material has before it breaks.

Why is shear testing important?

Shear testing is essential in hundreds of industries because it provides valuable information about how materials behave under shear stress.

By subjecting materials to shear tests, researchers can understand how suitable a material is for its purpose, check whether it's safe to use, and ensure that it meets industry standards.

Let's look at some of the most common uses for shear testing in more detail.

1. Geotechnical engineering: Shear tests are a standard method for determining the strength of soils and rocks. Researchers typically use soil strength testing equipment to perform either the shear vane test or direct shear test to determine the strength of the soil. Researchers can use the information gathered to understand how much weight foundations or walls can bear.
2. Structural design: Engineers regularly use shear testing to assess the strength of structures like buildings and bridges, helping to ensure they are safe to use.
3. Rheology: Researchers may use shear tests to study the way that fluids and gels flow. The researcher will typically use a rheometer to understand the properties of a liquid. This is useful for pharmaceutical and cosmetic applications.
4. Adhesives: A scientist or product manufacturer may use a shear test to understand how different materials bond together. For example, in the aerospace and automotive industries, having strong adhesive joints that can securely hold together parts is essential.
5. Quality control: Manufacturers regularly use shear testing to assess the strength and durability of materials to ensure they meet regulatory standards.
6. Material development: Scientists and engineers may use shear testing to determine the properties of materials like plastics, metals, and composites. Shear tests can give us a better understanding of which materials are best suited to specific applications.

Shear testing applications: 7 common types

There are many variations of shear tests, each designed to serve a specific purpose in a particular setting. Let's look at 7 of the most common uses in more detail.

1) Shear Vane Testing

The shear vane test is typically used to measure the strength of soils. During the test, the researcher inserts a cylindrical vane into the soil sample and then rotates it to apply force. The amount of force applied to shear the soil is then used to calculate the soil's strength.

2) Direct Shear Testing

The direct shear test involves placing a substance between two plates. A horizontal force is applied through one plate while the other plate holds the substance in place.

The direct shear test is commonly used in geotechnical engineering shear strain tests to evaluate the strength of rocks or soil.

In the test, a researcher places a rock or soil sample in a shear box and applies a weight to the top of the sample. A shear force is then applied horizontally to begin deformation. Specific equipment, like direct shear testing machines, are designed to make direct shear testing easier.

3) Torsion Testing

The torsion test involves twisting a rectangular or cylindrical material until failure, while a torsion test machine holds the substance at both ends. Torsion testing helps evaluate the shear properties of metals, plastics, and polymer matrix composite materials.

Torsion testing is typically used in manufacturing, automotive, and aerospace industries as it allows researchers to develop materials that can withstand forceful shear loads.

4) Iosipescu Shear Testing

The Iosipescu test involves cutting v-shaped notches into a rectangular or square specimen and clamping it on both sides. Downward pressure is then applied to one side of the material to test its shear strength.

Iosipescu shear testing is primarily used for in-plane shear response testing and is typically employed to test composite materials. It is an important test for assessing the viability of construction materials.

5) Shear Punch Testing

In the shear punch test, a small disc is placed between two flat surfaces and compressed until a hole is punched through the material. The force required to punch the hole indicates how strong the material is.

Shear punch testing is commonly used in the construction industry to determine how strong certain materials are, such as asphalt or concrete mixtures.

6) Cutting Shear Testing

In the cutting shear test, the researcher places a sample on a flat surface. A blade is then lowered to slice through the specimen. The test is usually performed in controlled conditions using a shear blade.

Cutting shear testing is very popular in the food industry, as it helps determine bite force and food texture. The force required to cut through a sample of meat, fish, vegetables, or cheese indicates its toughness and firmness.

7) Lap Shear Testing

The lap shear test is commonly used to determine the strength and durability of an adhesive. During the trial, the researcher bonds two flat materials using an adhesive. A shear force is then applied to move the two specimens in opposite directions. The force required to break the bond indicates the shear strength of the adhesive.

Where can I find equipment for shear testing?

Certified MTP has an extensive supply of materials testing equipment for direct shear testing, shear vane testing, cutting shear testing, and more.

Whether you're looking for concrete testing, asphalt testing, aggregate testing, or soil testing equipment, our first-class products are designed to ensure you get accurate, reliable results every single time.

Looking for something specific? We offer a high-quality range of rheometers, shear blades, direct shear machines, soil moisture testing equipment, and vane shear testing equipment.

Can't find what you're looking for? Get in touch - our team of material testing specialists is on hand to help you find a product that meets your needs.